Subscriber&#39;s instrument for radio broadcast system of distribution



Ju ne 5, 1928. 1,672,373

E. E. CLEMENT SUBSCRIBERS INSTRUMENT FOR RADIO BROADCAST SYSTEM OF DISTRIBUTION Filed Feb. 20, 1925 4 Sheets$heet 1 -TnvenZ'or,

June 5, 1928. 1,672,373

E. E. CLEMENT SUBSCRIBERS INSTRUMENT FOR RADIO BROADCAST SYSTEM OF DISTRIBUTION June 5, 1928. 7 1,672,373

' E. E. CLEMENT SUBSCRIBERS INSTRUMENT FOR RADIO BROADCAST SYSTEM OF DISTRIBUTION Filed Feb. 20, 1925 4 Sheets-Sheet 5 I ing 6 I 1 log I l I I 68 L210 l i I l I l g k A {V A 0 J47 J42 110 12919 117 .ll /53' 10 1J0 June 5, 1928. 1,672,373

E. E. CLEMENT SUBSCRIBERS INSTRUMENT FOR RADIO BROADCAST SYSTEM'OF DISTRIBUTION Filed Feb. 20, 1925 4 Sheets-Sheet 4 1137 1 L L I 2 P45061604 38 fig a K I #0 mum/yea? 126 Patented June 5, 1928.

UNITED STATES 1,672,373 PATENT QFFICE.

EDWARD E. CLEMENT, OF. WASHINGTON, DISTRICT OF COLUMBIA, ,ASSIGNOR T EDWARD F. COLLADAY, OF WASHINGTON, DISTRICT OF COLUMBIA.

SUBSCRIBEBS INSTRUMENT FOR RADIO BROADCAST SYSTEM OF DISTRIBUTION.

Application filed February 20, 1825. Serial No. 10,533.

My invention relates'to radio broadcast distributing systems, the present applicafiled December 6, 1924, and Serial No. 3,861,

filed January 21, 1925, (Patent 1,577,108, March 16, 1926), while certain features such as the key set herein described and not claimed form the subject of my divisional 19 application Serial No. 47,5 19, filed August The object; oi the presentinvention is to provide subscribers telephone apparatus and broadcast receiving and selecting apparatus for use in a system otthe above type, which apparatuses may be combined to use certain parts in common for the two functions of telephone and broadcast reception, whereby the subscribers apparatus is sim- 22 plified. I

My invention is illustrated in the accompanying drawings, in which: 1

Figs. 1 and 2 illustrate, diagrammatically, the telephone exchange portion, and broad.- cast distributing portion, respectively, of a combined telephone exchange and broadcast distributing system.

Fig. 3 is a diagram of another form of subscribers apparatus.

the central ofice circuits of Fig. 2.

Fig. 5 is a side view, partly in section, of the subscribers control apparatus of Fig. 3. Referring to the drawmgs in detail, and first to Fig. 1, this shows the essential circuits of an ordinary telephone exchange system in which A and A are subscribers stations connected by line wires 85-86 and 69-70, respectively, to the central station G where they terminate on multi le jacks J and J respectively. These jac s are arranged to be interconnected through the usual answering and calling plugs P-P forming the terminalspf the usual common battery cord circuit shown. The central oiiice terminals of each line are provided with the usual line relay L, line lamp L and cut-off relay L. Where service is to be metered a recording meter M is also indicircuit arrangement here shown isthat of the standard multiple switchboard, common battery, telephgne'exchange system, and as such is well'understood in the art further detailed description thereof will be here de- Fig. 4 is a diagram of a modification of vidually associated with the line. Thus, the

ferred and brought out later in the descrip- 't1on of operation. Inaddition to the usual line terminal multiples 1, 2 and 3, representing multiples of the tip, sleeve and test or cut-ofi circuits, respectively, I provide a fourth conductor 4 leading from a contact on the line relay along with the multiple conductors 1, 2 and 3 to the broadcast distributing system diagrammed in Fig. 2.

Fig. 2 shows the broadcast distributing system of which the portion to the left of the dotted line is situated at the central oflice and connected with the subscribers telephone line terminal apparatus of the telephone central C (Fig. 1) through conductors 1, 2, 3 and 4, while the portion to the right of the dotted line in Fig. 2 is situated at the subscribers substation and connected with the subscribers telephone substation apparatus A (Fig. 1) through the multiple conductors 5 and 6. In Fig. 2 the subscribers line multiples '1-2 terminate in contacts 7-8 of an automatic selector switch 8. This switch is of a type well understood in the automatic telephone art in which movable contacts or wipers such as 7 and 8 are carried on a shaft lO-biased in a given normal position by a spring or other suitable means not shown and arranged to be stepped around by a stepping magnet 11 through a stepping-pawl 12 and a ratchet 13. Also, as is usual with such switches, it is. provided with a dog 14, arranged to be thrown out of-engagement with the ratchet 13 and tothrow the ste ping pawl 12 out of engagement when the og is tripped by the actuation of the release magnet 15, the energization of the release magnet 15 efiecting the tripping of the dog 14 through-an extension 16 on its armature 17 pivoted at 18. 95 To hold up the armature extension 16.until the switch has released, a trip detent 19 is provided which is pivoted at 20, and arranged to be held normally out of engagement with the hook 21 on the armature 17 100 by a cam 22 on the switch shaft which permits the detent 19' to move into operative relation with the hook 21 whenever the switch is in oil-normal position. Mounted on the switch shaft 10 are other pairs of wipers 105 23-24, 25-26, and 27-28. The switch .9

is provided with a contact bank containing rows of contacts 30, 31, 32 and 33 arranged to be engaged by the switch wipers 7-8,

23-24,ete., successively in the direction in- 110 contacts are here shown it is to be understood that they may be more or less in numher and that in any case the first few vertical rows of contacts are left blank or disconnected, for example, in the present case the first five, leaving the sixth veitical row of contacts the first ones that are connected with the operating circuits so that the switch must make five steps before effecting any circuit connections, after which thewipers will be moved successively to the sixth, seventh and eighth vertical rows. The purpose of providing this lost motion or blank steps will be made clear in the description of operation. The switch wipers 23--24 connect withthe adjacent terminals of the winding 34'35 of a repeating coil 36, the remote terminals of which windings connect to the plate and filament of the audion tube 37.

The switch wipers 25-26 connect to the grid and filament of the tube 37, while the wipers 26 and 28 form the terminus of the filament of the tube 37. The wiper 27 is connected to the multiple'test wire 3, leading into Figul. The contacts in horizontal row 30 are connected as multiple pairs, the

upper and lower members being connected respectively to the remote terminals of the coils 38 and 39 of the repeating coil 36 I through the conductors 40 and 41, the conductor 41 connecting with the coil 39 through a sleeve or Iinesupply relay 42,

shunting resistance 43 and conductor 44.

The adjacent terminals of the coils 38 and 39 are connected to the plus and minus side of the exchange common battery B through conductors 45 and 46, and bus conductors 47 and 48, respectively. In the horizontal row ofcontacts 31, the sixth, seventh and eighth pairs are connected individually to the bat teries B, B and B respectively. In the horizontal row of-contacts 32, the sixth, seventh and eighth pairs are connected, respectively, to the different program transmitting sets P, P", and P, the lower contacts of the sixth, seventh and eighth pairs bein connected respectively to the bus wires 0 filament batteries F, F, and F respectively. In the horizontal row of contacts 33 the upper members of each pair are, connected in multiple to the conductor 49 which supplies battery current for the test by its connection through repeat relay 50, conductor-46 and bus 48 to the central ofiice com.- mon battery B. The .lower contact members of the horizontal row 33 are connected individually to the upper bus wires of the difierent fitment batteries F, F, and F.

magnet 15 have their windings connected in multiple, one side to ground andthe other side through conductor 51 to an impulse wire 4 leading into Fig. 1 where it terminates in a front or normallyopen contact 52 of the line relay L, which contact is engaged by the armature 53 connected through wire 54' to-the exchange comin'on battery B. The conductor 51 is also connectedin multiple to a normally open contact 55 engaged 1 by the armature 56 of the relay 50, the ar mature 56 being connected by way of conduct'ors 46 and 48 to the exchange common battery B. The repeat relay 50 is controlled by the sleeve relay 42 through the armature 57 which is arranged, as shown to close a shunt around the winding of the relay 50 by way of resistance 58, armature 57 and conductor 59. The-program transmitting devices P, P, and P are preferably radio receivers of a type adapted to receive radio broadcast matter from near or distant points and amplify and 'relay the same at audio frequency on to their respective bus wires 66, 67 and 68 respectively, the amplification being effected in any suitable manner such as by heterodyning detection and long. wave amplification or a combination of short wave amplification, detection and long wave amplification, the latter being preferably limited so as to allow a second stage to be made between the bussesand' the ultimate receiver. In this casethe ultimate receiver is the subscribers broadcast receiver 64 and the second stage of amplification is effected through an audion tube 37 individual to each line.

In the operation of the arrangement shown in Figs. 1 and 2, the subscriber at station A operatively connects his broadcast receiving or extension set A to the line by inserting'the receiver plug P in the jack J 2 which connects his receiver 64 across the line multiples 5 and 6 through the booster coil windings 6065 and condenser 266 in series, and closes a path for direct current between the multiples 5 and 6 through coil 60, lower spring of jack J transmitter 62, and automatic dial 63. This energizes the subscribers line relay at the central oflice in the usual manner by current from the central otfice common battery B, which energizing circuit may be traced, from the grounded side of central 'ofiice common battery B, conductor 68, right hand winding of line relay L, line conductor 69, to subscribers substation A, line multiple 5, to subscribers broadcast receiving set A (Fig.

2), coil 60, transmitter 62, contacts of dial 63, conductor 6, 70, left hand winding of line relay L and back to the battery B,

' scriber wanting broadcast service will immediately operate his dial to break and make his line circuit a certain number of times according to the particular program he desires which breaks and makes will cause his line lamp to flicker instead of glowing steadily and so indicate to the telephone operator that the subscriber is not calling for a telephone connection but is automatically setting up his connection for broadcast reception. As the dial 63 is of the well known type used in automatic telephony and well understood in the art, it will not be necessary to describe the same here in detail and it suffices to say that it operates automatially to effect one or a series of breaks of brief duration in the line circuit according to the setting of the dial each time it is set and released. The first closure of the line and energization of the line relay L completes an energizing circuit for the stepping magnet 11 (Fig. 2) which may be traced from the free side of the common battery 13 through circuit elements 54, 53, 52, 4, (into Fig. 2), 51 to stepping magnet 11 and release magnet 15 in multiple and thence through ground back to the grounded side of battery B. It is to be noted here that the release magnet 15 is made sluggish in its action so that it will not. respond to'the energizing current until after a lapse of time much longer than the interval between the breaks and makes of the subscribers dial 63 so that when the subscriber first closes his circuit, as just described, the stepping magnet 11 will first operate to step the switch 9 around one step releasing thedetent 19 after which, the time period of therelease magnet 15 having lapsed, this magnet will actuate its armature to move the hook 21 up into engagement with the detent 19 and the extension 16 into engagement with the dog 14 which disengages the dog from the ratchet 13 and also throws the pawl 12 out of engagement with the ratchet, thus causing the switch to release and return to normal position whereupon the cam 22 will throw the detent 19 out of engagement with the hook 21 and leave-the armature 17 free to return to normal position when the magnets becenie deenergized. In the case of a call for telephone connection this deener-' gization of the magnets would occur when the telephone operator, in answering, inserts the plug P in the jack J which would operate the line cut-01f relay L in the usual manner causing the line relay L to retract its armature 53 and open the circuit of the stepping and release magnets 11 and 15. To prevent the subscribers broadcast selector switch 9 from being stepped around and connecting broadcast matter on to his line 'due to one or more accidental breaks in his line circuit while the subscriber is waiting for telephone operator service, the selector switch 9 is provided with several blank contacts preceding those representing the different broadcast programs. In the present illustration the first five contacts are left blank, the series of active contacts beginning with those of the sixth vertical row, as indicated in Fig.2, where the blank contacts are not shown, it being understood that the switch must make five steps before its wipers engage .the first set of active contactsl Thus if the subscriber, while waiting for an operator should accidentally, momentarily open his line or impatiently operatg his switchhook a few times, the connector switch would simply step around over a few or the blank contacts and release as before described when the operator plugged in with her-answering plug. Returning now to the subscribers selection of a desired broadcast program, the subscriber, shortly after the initial closure of his line effected by his insertion of the plug P in the jack J and before the line lamp has been energized sufliciently long toindicate 'a telephone call to the operator, sets his dial to a number corresponding to he number of .the broadcast program he wishes to receive, which in the present case would be some number above five, and permits the same to,release producing a number of breaks corresponding to the setting of the dial. Assuming the setting to be eight the d al upon release will cause the'line circuit to be momentarilyppened eight times. The first five breaks in the line circuit will-cause the armatu'ref53 of the line relay to open and close its connection with the contact 52 five times, thus ste ping the selector switch around to the fth contact, 'the period of closure of the contacts 5253 being sufiiciently brief to prevent actuation of the re- 46, winding of repeat relay 50, conductor 49, upper member of the sixth contact of horizontal row 33, switch wiper 27, conmon battery B. Energization of repeat relay 50 causes, its armature 56 to engage the contact 55 thus maintaining the stepping magnet 11 energized by current frombattery B through circuit elements 48, 46, 56, 55, 51, 11 to ground and back to battery B, while the energization of the cut-off relay L (Fig. 1) disconnects the line relay L in the usualmanner which becoming deenergized releases its armatures 71,-53, extinguishing the line lamp and 0 ening the circuit through conductor 4. imultaneously with the energization of the cut-off relay L and repeating relay 50, the sleeve relay 42 is energized by current from the common battery B through the circuit elements 48, 46, 39, 42, 41, lower member of the sixth contact in the horizontal row 30, switch wiper 8, line multiple 2 into Fig. 1, line wire 70, multiple wire 6, into Fi 1, through circuit elements 63, 62, 60, 5 into i .2, 69, 1, into Fig. 2, 7, 40,38, 45, 47, an back to the grounded side of the common battery B. Energization of sleeve relay 42 causes its armature 57 to be attracted and complete a shunt around the winding of repeat relay by way of circuit elements 58, 57 and 59, which shunt causes'the relay 50 to become deenergized and retract its armature 56 opening the circuit of the stepping magnet 11 and causing it to return to normal ready for the'next step. The next or seventh momentar' break in the subscribers line circuit, which follows. immediately, eifects a momentary release of the armature 57 of sleeve relay'42 which causes a momentary energization of the repeat relay 50 which in turn effects a momentary closure of the contacts 56--55 and a momentary energization of the stepping magnet 11 to step the switch wipers around to the seventh vertical row of contacts. The energizing circuit of the stepping magnet may be traced from the common battery B. through circuit elements 48, 46, 56, 55, 51, and 11 back to the grounded side of battery B. Similarly, the next or eighth momentary break in the line causes the stepping magnet 11 tobe again momentarily energized and step the switch wipers around into engagement with the eighth vertical row of contacts.

After the eighth momentary break in the line circuit-the subscribers dial 63 comes to crest and maintains 'the line' circuit closed. The line now being closed, the sleeve relay 42 is maintained energized which maintains the repeating relay 50 deenergized by virtue of the closure of the shunt around its winding which in turn maintainsthe circuit of the stepping and. release magnets 11 and 15 open at the contacts 55-56. The switch wipers thus come to rest'on the eighth vertical row of contacts, maintaining the input and jack connection P -J. As the sleeve ing used for the reception ofbroadcast so peating coil of the well known type having a the four windings 34, 35, 38, 39 on a common magnetic core the output or plate circuit of the tube 37 is coupled to the subscribers linethrough the coils 38-39 which are included in series in the subscribers line circuit as hereinbefore traced. The filament circuit of the subscribers audion tube 37 may be traced from filament battery F individual to the programv trans-. mitter P over the circuit elements 79, lower member of bus wire 68, 26, filament of audion tube 37, filament rheostat 80,28, 81, 82, back to battery F As the winding 60 of the booster coil 61 at the subscribers broadcast receiving set A? is included in series in the line, the broadcast matter coming thereover is repeated in'the winding 65 which reproduces the signal ,in .the subscribers receiver 64 over a circuit which may be traced from 65, through circuit elements 266, 63, 62, and through the receiver 64 back to winding 65. by way of the plug relay 42 is held energized during the subscribers use of his linefor receiving broadcast, should a telephone operator test one of his multiple jacks in the usual manner before establishing a connection therethrough to his line, instead of the ordinary busy test of a click in the ear, she.will receive a special tone test which will indicate that the line is not busy for telephone use but is be that if the call is an emergency one the operator may plug in regardless of the busy condition. =Thus a special tone test is effected by the usual tone test apparatus indicated in Fig. 2 as consisting of the inductance 87 connected in series with a circuit breaker 88 and inductively related to the coil 58 in series in the test circuit. The energizing circuit of the coil 87 may be traced from the common battery B through the circuit elements 48, 46, 87. 88; back through ground to the battery B.

When the subscriber wishes to discontinue the broadcast reception he withdraws the plug-P which opens the line circuit at the jack contact 89. This deprives the sleeve relay 42 of current whereupon its armature 57 is retracted removing the shunt from the repeating relay 50 which thereupon becomes energized and closes the actuation ment w1th the dog 1 1 to trip the same which in turn tripsthe pawl 12 allowing the switch to return to normal, hook 21 engaging the detent 19 which holds the armature 17 in its actuated position during the restoring movement of the switch and until the switch reaches the normal position.

whereupon the cam 22 operates to disengage the detent 19 from the hook 21 and permit all parts of the switch to return to the normal position shown. When the switch in restoring moves its wipers ofi the sixth vertical row of contacts the circuit of repeat relay 50 is broken at the wiper 27, and the repeat relay 50 deenergizing opens the circuit of the magnets 11 and 15 at the contact 55-56. This puts all the circuits and apparatus in the normal condition shown in Figs. 1 and 2. 7 Q

. For metering the subscribers use of the radio broadcast service on a basis of time use, ameter controlling actuator90 (Fig. 2) is arranged to control-the subscribers telephone meterM (Fig. 1) through the operative connection of the switchcircuits of Fig.

2 with the subscribers central oflice line terminal circuits. be traced from the meter generator 91' (Fig. 2) through commutator 90, switch 92, bus wire 93, switch 94, wire 49, the upper member of one of the contacts in the horizontal row 33, wiper 27, test Wire 3, into Fig. 1, wire 95, high voltage winding 96, of the meter M, to ground and back to the rounded side of the meter generator 91 Fig.2). When the meter armature 97 is attracted a suflicient distance to close the contact 98 the low voltagewinding 99 of the meter 1S closed thus aiding in the further attraction of the armature and the actuation of the meter as well understood in the art, WhlCh will be repeated at intervals according to the intervals of the GlOSIDg an opening of the circuit meter commutator 90. These periodic re istrations oi the meter during use of the roadcast ap aratus Wlll of course be addedto those pro uced by the actuation of the usual, telephone operators metering key 100, so that the subscribers use of the broadcast service is charged in the same units as that of the telephone use 3 and the amount of service represented by a unit charge varied according to the s eed of operation of the commutator 90. W ere the service to some of the lines'is tobe given This controlcircuit may' free the switch 94.- individual to the line is opened and where the service is to be given free to all or a group of lines the; switch 92 I the same as the line wires 69-70 of Fig.

1. The subscribers telephone apparatus A and its circuit connections are the same as 7 that shown at A of Fig. 1, thatis, the ordinary Western Electric common battery type of subscribers set. The subscribers roadcast set (Fig. 3) comprises a loud speaker receiver '101 connected through a connecting and signaling key 102 with the circuits of the telephone set A. A transmitter 103 is also associated with the subscribers set A and'arranged to be connected in circuit through the opening of a shuntin switch 104. The subscribers key 102 is s own in detail hereinafter. For the present it suffices to point out the essential functional elements indicated diagrammatically in Fig. 3. These consist of the starting andselecting button 105 and the 06 or disconnect button 106' arranged to be normally held in'the position shown b suitable retractile springs 107 and 108.

he button 105 is so' arranged that when it is pressed downpart 'way it' will close together thethree contact springs 109-110-111 and become locked against return movement upward by engagement of a lockin plate 112 with the upper edge of the note 113, but ma be prgssed the normal condition of disuse shown, the (1 line circuit 69-70 is open at the subscribers station except for ringing through the rin er Q and condenser 115. The subscri ers loud speaker 101 is arranged to be connected upon closure of the contacts 109-,-

110-111 in the usual local or secondary circuit including the condenser and secondary I? of t e subscribers booster coil I. This circuit may be traced from the lower terminal of the secondary coil I througlTextension wire'116, loud speaker 101, contacts 111-110-109, contact 114, shunt switch 104, extension 117, line conductor 70, condenser 115, and back to the upper terminal of secondary coil I As all three of the contacts 109110111 are closed at the same time,

the line circuit is closed through the primary winding I by way of line conductor 69, winding 1, extension conductor 118, contacts109,110-111, contact 114,- extension conductor 117, back to the other line conductor 70. By opening the shunt switch 104 the transmitter 103 may be included in this it several pushes to cause the contact 114 to open and close in rapid succession. The

first downward movement of the button 105 closes the line circuit 69-70 which closure may be traced .from line conductor 69 through the circuit elements I, 1.18, 109- 110111, 114, 117, to line conductor 70, this circuit being immediately opened at the contacts 114 upon the completion of the downward 'movement of the button and again closedwhen the button is permitted to rise to the limit permitted by the locking plate 112, the line circuit being again opened at the contact 114 each time the button 105 is.

pushed down. This closure of the line circuit with subsequent successive breaks causes the switching apparatus of Fig. 2 to be operated in the same manner asthat before described in connection with the operation thereof by the subscribers sending ke 6'3 (Fig. 2), the switching device establis ing connection with one of the program devices P, P, or P, according to the number of times the subscribers button 105 (Fig. 3) is actuated. When the subscriber desires to discontinue the broadcast service he has only to depress the button 106 which releases the button 105 and restores the circuits to normal condition.

In Fig.- 4 is shown diagrammatically the arrangement of switching apparatus especially adaptable to use with the form of subscribers apparatus shown in Fig. 3. In the switching arrangement of Fig. 4 the subscribers line terminal multiples 1, 2, 3 and 4 extend from the telephone switchboard circuits of Fig. 1. The multiples 12 terminate in a jack switch 119, arranged to extend the connection through contacts 120 and 121 to conductors 122 and 123 leading to the common batter B through the secondary windings of t e repeating coils 124 and 125 and sleeve relay 42, in series. The

signalin conductor 4 terminates at one terminal 0% the signaling lamp 126, the other terminal of which is grounded, while the test con ductor 3 is arranged to be connected through a normally 0 en contact 127 of the sleeve relay 42 to a c aracteristic busy tone 'upon' insertion in the jackcloses the con tacts 120-121 and 133, the closure of .the contacts 120121 eflecting an extension of the line multiples 12 as previously described, while closure of the contact 133 extends the signal conductor 4 through to conductor 134 connected through a normally closed contact 135 of the relay 42 to the battery B. The selector switch S' contains bank contacts ss's connected to separate pairs of bus wires 136 (carrying N o. 1 program), 137 (carrying No. 2 program), and 138 (carrying No. 0 or announcements). ,The switch S does not need to be restored to zero,-and may be left always in the last position to which it has been moved, since the wires 139-140 leading to the wiper arms of the switch are cut-off at the relay contacts 130131 when the apparatus is in disuse. The No. 1 and 2 program busses are connected to the output circuits of broadcast.

relay receivers 141 and 142, respectively, and the announcement buswires 138 are connected to a local distributing apparatus oramplifier AS with a microphone This position or equipment on the radio switchboard corresponds to the information operators position on a telephone switchboard.

The operation of the system using the subscribers apparatus of Fig. 3 with the central oflice circuits of Figs. 1 and 4, isas follows: The subscriber desiring broadcast service calls as before, by making short 010- sures of-his line with the starting button after first pushing it down beyond the locking position. These short closures flash both the telephone switchboard lamp L (Fig. 1) and the broadcast switchboard lamp 126 (F 1g. 4). The operator at the broadcast service board perceiving the flash of the lamp 126 knows that the subscriber wants broadcast service and responds by inserting the dummy plug 132 in the jack switch which extends the subscribers line multiples 12 through contacts 120121 to the con duct-ors 122-123, thereby completing the subscribers line circuit through the secondary windings of the repeating coils 124125 which circuit may be traced from battery B (Fig. 4) through thecircuit elements, secondary winding of repeatin% coil 124, 122, 120, 1, into Fig. 1, 69, into. ig. 3, I, 118, 109 11c 111, 114, 117, 70, into Fig. 1, 2, into Fig. 4, 121, 123, 42, and through secondary winding of repeating coil 125 back to battery B. As this circuit includes windings of the relay 42 this relay is energized closing the input circuit of the subscribersline tube 37 onto the wipers of the switch S by way of contacts 130131.and conductors 139-140, and as the output circuit of the tube 37 includes primary windings of'the repeating coil 124-125 the subscriber now hears, on his loud speaker 101 (Fig. 3) one of the broadcast programs or the announcements from the announcer bus according to the position of the switch S (Fig. 4). If it is one of the programs that he receives and he desires to select some particular item, he can by means of the button 105 (Fig. 3) propel the wipers of the switch S around step by step until they come in contact with the bank contacts 8 connected" to the announcers bus 138,- and by listening, he will hear a continuous announcement of the items then upon the busses, the items to follow, the numbers or call letters of the stations from which the said items are being sent,

and any other interesting information connected with the same. Having ascertained a whole list of items available for the moment with the number of theprogram busses on which they are to be found, the subscriber mayby operation of his button 105 operate the switch to start from the announcer bus as zero and step around to the desired bus such as 137, 136, etc.

When the subscrlber desires to discontinue. the broadcast service, he actuates the off or release button 106 to release the button 105 and restores his receiving apparatus and line circuit to the open or normalcondition whereupon the sleeve relay 42 (Fig. 4) becomes deenergized opening the input circuit of the tube 37 at contacts 130131 and energizing the signal lamp 126 in a c rcuit which may be traced from battery B (Fig. 4) through circuit elements 135, 134, 133, 126 to ground and back to battery B. The broadcast service operator perceivlng the steady glow of the lamp 126 knows that the subscriber desires disconnection and thereupon withdraws the plug 132 which opens the contacts 120- 121- -133 of the jack switch 119. The opening of the contact 133 extinguishes the lamp 126 while the opening of contacts 120121 opens the connection across the subscribers line mul- 142 at the lower end of the right and disengage the contact 114.

The right hand side of the member 146' is made straight or parallel in its direction of movement, above the cam surface 147 so that when the member 146 is moved downwardly to operate the spring contacts 109, etc., a continued downward movement will maintain the contacts closed. As will be seen from the drawing, the cam surface 148 is placed above the cam surface 147 while the cam engaging portions of the springs 109 and 149 are at substantially the same level, so that upon the first portion of the downward movement of the member 146 the contact springs 109110-111 will be actuated, and upon further downward movement the spring 149 will be actuated. Below the mounting-plate 141 near the upper portion of the cam member 146 is mounted a locking plate 112 mountedon springs 150 arranged to normally hold the plate in the position shown. The locking plate-112 is provided with an aperture 151 through which the cam member 146 passes, the right hand edge 152 of the aperture being round or beveled so as tohave easy cam action with the cam projection 113 on the member 146. This cam member 113 is arranged, upon downward movement,-to throw the locking plate 112 over to the right against the ,tenslon of the spring 150 until the cam'member 113 passes below the edge 152 whereupon the plate moves back I bringing the edge 152 over the top edge of the cam 113 thus preventing upward movement ofithe button 105 beyond this position, the button 105 and cam member 146 being tensioned upwardly by the compression spring 107 arranged to. engage the stem 145 through the cross pin 153, at its upper end and to bear against the base member 143 at its lower end. As the button 105 is locked only against the upward movement, it is free to be pushed further downward to operate the spring 149 and to re turn out of engagement therewith without permitting the contacts 109-110-411 to become separated. To release the button 105 and permit it to return to its normal position, the off or disconnect button 106 is top of plate 141 and base. 143 through its key stem 154 and guide stem 155 and is normally held in the position shown under tension of the spring 108 engaging the key provided which also has bearing in the tom. The key stem 154 also passes'through an aperture 158 in the lock plate 112 and is provided with a cam' surface 157 arranged upon the downward movement to engage with the right band edge' 159 of the aperture 158 and move the plate 112 over to the right a suflicient distance to cause the edge 152 to disengage the upper edge of the cam member 113 and release the key 105 under tension of the spring 107. It

'will thus be seen that in operation when the button 105 is pushed down half way it will become locked against further upward movement and maintain the cont-acts 109- 110-111 closed during further downward vand upward movements of the cam member 146 below this half position which latter downward and upward movement will effect an opening and closing of the contacts 114, and that when the finger of the operator is removed from the button 105 "it will remain locked in the half position leaving all the contacts closed until the release button 106 is depressed permitting the button 105 to return to the normal position shown and permit the contacts 109,110111 to assume the open normal position shown.

While I have herein shown and described certainspecific embodiments" of my invention for-the'sake of disclosure, it is to be understood that the invention is not limited to such specific embodiments but contemplates all such modifications and variants thereof as fairly fall within the scope of the appended claims.

What I claim is I 1. In a broadcast distributing system, a central station, a plurality of subscribers stations, line wires connecting the central station with each subscribers station, means at the central station for transmitting a plurality of broadcast programs to said subscribers stations over said wires, automatic selecting means at the central station, telephone apparatus and broadcast receiving apparatus at each subscribers station opera tively connected with its associated line wire, said telephone apparatus comprising a booster coil connected in circuit with a telephone receiver and transmitter, and said broadcast receiving apparatus comprising a 'receiveranda line bridging circuit arranged .to be connected in place of said telephone set central station, a plurality of subscribers stations, line wires connecting the central station with each subscribers station, means at the central station for transmitting a plurality of broadcast programs to said subscribers stations over said wires, automatic selecting means at the central station, telephone apparatus and broadcast receiving apparatus at each subscribers station operatively connected with its associated line wire, said telephone apparatus comprising a booster coil connected in circuit with a telephone receiver and, transmitter, and said broadcast receiving apparatus comprising a receiver and a line bridging circuit arranged to be connected in circuit with the said booster coil in place of the receiver and transmitter of the telephone set, respectively,'together with means included in said line bridging circuit for controlling said automatic selecting means.

3. In a telephone exchange system having a central station and subscribers substations connected therewith with telephone receiving apparatus at each substation comprising a booster coil transformer having its secondary winding connected in circuit with the usual telephone substation receiver through switchhook contacts and its primary winding connected in circuit with the substation transmitter through switchhook contacts, the combination of means at the central station for transmitting a broadcast program to the EDWARD E. CLEMENT. 

